Electric switch



March 26, 1940. D. G. mem. 2,195,251

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Inventor* Donald G. Kimball,

1S Attorney.

March 26, 1940. n. G. KIMBALL ELECTRIC swn'ca VImm: April 29. 1939 3Sheets-Sheet 2 Inventor': Donald C3. Kimball,

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Patented Mar. 26, 1940 PATENT OFFICE ELECTRIC SWITCH Donald G. Kimball,Stratford, Conn., assigner-to General Electric Company, a corporation ofNew York Application April 29, 1939, serial No. 270,882

13 Claims.

This invention relates to electric switches, and more particularly toelectric switches for use with electric ranges.

An object of the invention is the provision of 5 an improvedconstruction and arrangement in switches of the type described, in whichthe switch mechanism is arranged compactly within the switch housing andin which the switch mechanism may be manufactured at low cost.

l In the accompanying drawings Fig. 1 is a plan view of the switch withthe front cover removed showing the positioning mechanism; Fig. 2 is asectional view through the switch along the line 2 2 of Fig. 1; Fig. 3is a sectional View through l5 the switch at right angles to the showingof Fig. 2 along the line 3 3 of Fig. 2; Fig. 4 is a view looking at therear of the switch with the cover removed substantially along the line4-4 of Fig. 2; Fig. 5 is a view of a modiiied form of the in- 20 ventionsimilar to the showing of Fig. 4; Fig. 6 is a view of a portion of theswitch mechanism; Fig. 7 is a diagrammatic view of the switch of Figs. 1to 4, inclusive, showing the arrangement of the operating cams; Fig. 8is a diagrammatic 25 view of the modified form of switch shown by Fig. 5illustrating the arrangement of the operating cams; Fig. 9 is adiagrammatic view of the switch of Figs. 1 to 4, inclusive, showing theswitch connected to a heater system, and Fig. 10

0 is a diagrammatic view of the modified form of switch of Fig. 5,likewise showing this switch connected to a heater system.

In the accompanying drawing, the switch designated generally by thenumeral is provided with a housing 2| having recesses 22 and 23 onopposite sides thereof which are separated by a partition 24. The recess23 is formed in the front part of the housing and receives a switchpositioning mechanism to be described later, while l1 the recess 22 isformed in the rear portion of the housing and is adapted to receive theiixed and movable contacts of the switch. 'I'he recess 23 is closed by acover plate 25 while the recess 22 is closed with a cover plate 23. Boththe cover 4f plate 26 and the housing 2| are formed of insulatingmaterial, for example, a phenolic .condensation product and filler whilethe cover plate 25 may or may not be formed of insulating material andis shown being formed of metal.

10 The portion of the switch mechanism comprising the stationary andmovable contacts is located within the recess 22 and is shown moreparticularly by Figs. 2. 3 and 4. 'I'hese elements are arrangedsymmetrically within the confines ab of the recess 22 with the movablecontacts disposed around the periphery of the wall of the recess. 'Ihemovable contacts include flexible spring blades which are arranged attwo difierent levels one above the other. These levels will bedesignated hereinafter as "lower and upper" levels, the contactsdisposed at the lower level being located in the front of the housing,as shown by Fig. 2, and being shown in plan view by Fig. 3, and thecontacts disposed at the upper level being located at the rear of thehousing, as shown by Fig. 2, and being similarly shown in plan view byFig. 4. By this arrangement it is possible to secure double the numberof contacts within the area of the recess and, at the same time, providea switch mechanism which is of a rugged and compact nature.

Referring now to the fixed contact means of the switch mechanism aterminal member 21 is secured to the rear face of the housing by meansof a screw 28 tapped into a wall of the housing. The terminal member 21,in this case the first terminal member, is provided with two integralarms 29 and 30 having contact buttons 3| and 32, respectively, at theirouter ends for engagement with movable contacts. The contact buttons orsurfaces 3| and 32 extend in opposite directions and are located at twodifferent levels, the contact button 32 being located at the front orlower" level and the contact 3| being located at the rear or upperlevel. A stationary contact element 33 is mounted at the bottom of therecess opposite the terminal member 21 and is electrically connected bymeans of a screw 34, lox' other suitable fastening means, to a terminalmember 35, in this case the second terminal member, which is mounted onthe front face of the housing, as shown by Fig. 1. 'Ihe contact element33 is provided with two integral contact arms 36 and 31 each providedwith a contact button or surface 33 and 39, respectively, and whichextend into the recess in opposite directions similar to the contactsurfaces on the terminal member 21. As shown most clearly by Figs. 3 and4, the contact 38 is located at the "upper level in the recess while thecontact 39 is located at the "lower level. A terminal 40, in this casethe third terminal member, is located within the recess on a sideopposite that on which the previously described terminal members aremounted and is provided with an integral extension 40 arranged along thewall of the recess, the latter being formed with two integral arms 4|and 42 having contact buttons or surfaces 43 and 44, respectively. Asshown most clearly by Fig. 2, the contact button 4| is located at theupper level while the contact button 42 is located at the lower level.

In the form of the invention illustrated, it will be noted that therecess 22 is of substantially rectangular coniiguration, and that theterminal members 27 and 35 are located at opposite corners of the recesson a side opposite from that at which the terminal member is located.The terminal member 40 is located at a point midway between the cornersof the recess on the opposite side. This means that the variousstationary contacts formed on the contact arms of the terminal membersare located substantially equidistant from the geometric center of therecess 22 for cooperation with a single switch operating means, therebyproviding a compact arrangement of the switch elements. Each of theterminal members is provided with a terminal screw for clamping anelectric conductor.

The movable contact means includes a plurality of iiexible springcontact blades carried by relatively rigid strap members. To this end, astrap member 46 is provided with aleg 41 disposed in a groove 48 in thewall of the recess and secured to the leg is a flexible spring contactblade 49. One end of the blade is bent as a U and spot welded, orotherwise secured, to the leg 48, while the other end of the blade isprovided with a contact button for engagement with the contact button 32on the terminal member 2l. Another strap member 5| is provided with aleg 52 seated in a groove 53 in the wall of the recess. Attached to theleg 52 is a flexible spring contact blade 54. One end of the contactblade 54 is bent in the form of a U and spot welded or otherwiseattached to the leg 52 while the other end of the contact blade isprovided with a contact'button 55 for engagement with the contact button38. It will be apparent from an examination of Figs. 3 and 4 that thestrap members 4G and 5! are seated in a wall of the recess between thefixed terminal members 2l and 35, and that they are separated by aportion of the wall of the recess which insulates them from one another.The contact blades themselves extend in opposite directions andcooperate with the corresponding terminal members 2l and 35 at oppositesides of the recess. As shown most clearly by Figs. 2 and 4, the contactblades are disposed one above the other and are separated from eachother by a distance suiicient to insulate them from one another. Thestraps 46 and 5| are exposed and lie nat on the upper or rear surface ofthe housing. They are electrically interconnected by means of aconducting strip 56. The strip 56 is secured at one end to the strap 46by a screw 51, or other suitable fastening means, while the other end ofthe strip is secured to the strap 5I by a screw 58. The strap 5i andscrew 58 cooperate to form terminal means for receiving an electricconductor for a purpose to be described later. By the constructiondescribed it will be seen that the movable contact blades are arrangedin pairs be tween the corresponding fixed terminal members 21 and 35.

Similarly, a pair of the movable contact blades is disposed between theterminal members 35 and 40. To this end, a strap 59 is provided with aleg @il seated in a groove in the wall of the recess for mounting aexible spring contact blade 6i at the lower le'vei in the recess. At oneend, the contact blade is bent in the form of a U and is electricallyconnected to the leg 6D by spot welding, or the like, while the otherend of the 2l is a third pair of contact blades.

blade is provided with a contact button 62 which cooperates with thefixed contact 39. Another strap member 63 is provided with a leg 64mounted in a groove in the wall of the recess and carries a contactblade 66. One end of the contact blade is bent in the form of a U andelectrically connected, as by a spot weld, with the leg 64, while theother end of the blade is provided with a contact 61 cooperating withthe fixed contact 43. The strap 63 is provided with a terminal screw 68for receiving an electric conductor for a purpose to be described later.The other strap 59 is provided witha screw 69 engaging one end of ashorting strip 10. The pair of contact blades 6| and 66 are disposed inopposite relation one above the other similar to the other pair ofcontact blades 49 and 54.

Disposed between the terminal members 40 and A strap 1| having a legportion 12 is mounted in a groove in the wall of the recess and carriesa flexible spring contact blade 13. One end of the blade is bent in theform of a U and spot welded, or otherwise secured, to the leg l2, whilethe other end of the blade is provided with a contact button 14 forcooperation with the stationary contact 44. Another strap member 15having a leg portion 16 mounted in a groove in the wall of the recesscarries a Contact blade Tl overlying the contact blade 73. One end ofthe contact blade ll is bent in the form of a U and is spot welded, orotherwise secured to the leg 16, while the other end of the bladecarries a contact button 18 for cooperation with the xed contact 3l. Thepair of contact blades 13 and 11 are disposed in opposite directions andare placed one above the other similar to the blades of the pairs ofcontacts previously described. The strap H is provided with a terminalscrew 19 which is adapted to receive an electric conductor for a purposeto be described later. In addition, the terminal screw acts to securethe other end of the shorting strip 10 to the strap 1|. The strap l5 islikewise secured to the snorting strip 10 by a screw 80, or othersuitable fastening means. In this manner the contact blades 6l, 13 andIl are electrically interconnected by the shorting strip '10.

By the construction described, it will be seen that various ones of theContact blades are arranged in pairs between the respective xedstationary contacts or terminal members, and that are arrangedsymmetrically about the geometric center of the recess 22. The contactblades of each pair are placed one above the other and the contactbuttons face in opposite directions so that the blades may cooperatewith a corresponding fixed contact. The movable contact elements may beeasily assembled within the recess simply by slipping the leg portionsof the strap members into the corresponding grooves in the walls of therecess where they are held in position by the cover 26. The strapmembers are made of relatively heavy sheet metal and hold the exiblespring contact blades rigidly in position. Since each of the strapmembers is identical in size and shape and each of the fiexible blademembers and contact buttons are similarly identical in size and shape,these parts may be manufactured from single sets of dies and assembledtogether before being inserted within the switch housing. By providingthe end of each of the contact blades with a U bend, it is possible tospace the contact blades themselves from the wall of the recess leavinga space between the varicus blades and the walls of the recess forreceivlng the extending ends of the terminal screws which are mounted onthe strap members. In addition, the U bend makes it possible to providea contact blade which may be moved a sufficient distance from the fixedcontacts to insure completev interruption of the circuit withoutnecessitating a contact blade of undue length so that a more compactswitch structure is attained.

In order to cooperate with an operating mechanism, each one of thespring contact blades is provided with a slider 8|. Each slider has anintegral flange 82 which is spot welded or otherwise secured to thecorresponding contact blade. Cooperating with the sliders are aplurality of cam members 83 formed of insulating material, such as sheetfiber, and which are mounted on a shaft 84. The shaft is supported atone end in a bearing 84 in the wall of the cover 26 and at the other endin a bearing in the partition 24. The cam disks are separated from oneanother by plates 86 which may likewise be formed of insulatingmaterial, such as sheet fiber, and the cams and insulating separatingplates are assembled together on the shaft 84, in a manner shown by Fig.6, the assembly being held in position against an abutment 85 by awasher 81 having tangs 88 engaging serrations 89 on the outer peripheryof the shaft. 'I'he cover 26 is held in position on the casing by thescrews 90 and serves to hold the cam disk assembly in position withinthe recess. For connection with electric circuits, the various terminalscrews on the strap members extend through openings (not shown) in thecover.

The arrangement of the different cam members with the respective sliderelements and contact blades will now be described with particularreference to Fig. '7. In this figure the contact blades have been spacedapart to show the arrangement and shape of the individual carn disks. Inthe form of the invention illustrated, the switch is adapted to be movedto six positions which are indicated in dotted lines by the numerals I,2, 3, 4 and 5 on the respective cam members, the sixth position beingindicated by off. Inasmuch as the contact blades 11, 54 and 88 arelocated in the upper level of the recess, these contact blades will beoperated by cam members 9|, 92 and 93 through the medium of the sliders8|. The cam disk 9| cooperates with the contact blade 11 and is providedwith a depression to close the contact blade when the switch is moved tothe third position; the cam disk 92 operates with the contact blade 54and is provided with a depression to close the contact in the fourthposition; whereas, the cam disk 93 cooperates with the contact blade 66and closes this blade in every position of the switch except the ofiposition. The contact members 13, 49 and 6| are located at the "lowerlevel within the recess and are operated by the cam disks 94, and 96,respectively. To this end, the cam disk 94 cooperates with the contactblade 13 and is provided with a depression to close the contact blade inthe first position of the switch; the cam disk 95 cooperates with thecontact blade 49 and is provided with depressions to close the contactblade in the first and second positions of the switch; while, the camdisk 98 cooperates with the contact blade 6| and is provided with arecess to close the contact blade in the fifth position of the switch.Inasmuch as the cam disks are rigidly secured to the shaft 84, they maybe assembled as a unit, as shown in Fig. 6, prior to insertion in therecess. The cam disks are separated from one another by the insulatingplates A8|i which serve to guide the slider elements 8| over the outerperiphery of the respective cam disks without danger of the sliderbecoming unseated and moving into engagement with an adjacent cam disk.The two groups of cam disks,

which are located at the upper and lower level in the recess, areseparated by three insulating plates 91, as shown most clearly by Fig.6.

The positioning mechanism for the switch includes a star wheel 98provided with a plurality of teeth forming indexing depressions 99corresponding to the number of positions to which the switch is to bemoved, in this case, six. Two lever elements |00 are pivoted at one endby means of pins |0| on opposite sides of the shaft 84 and are providedat their other ends with rollers |02 which engage the teeth in the starwheel 98. I'he pins |0| rest in depressions formed in the partition 24and the cover 25. The rollers are pivotally mounted on pins |03 and areforced into engagement with the star wheel by a spring |04 which issecured at each end to one of the levers by means ofpins |05. It will beapparent that as the switch shaft is rotated the teeth on the star wheelwill force the lever members outwardly permitting the rollers |02 toroll over the edges of the teeth into engagement with the adjacentdepressed portions so that the different positions of thev switchmechanism are identified.

One of the uses to which the switch may be put is to control a heatersystem forl an electric range. As shown most clearly by Figs. 7 and 9.the switch has been connected to a heater system having two heater unitsA and B and the switch is designed to be moved to six positions givingan off and ilve varying heat values of the heater system. In connectingup the heater system to the switch one end of the heater unit A isconnected to the terminal strap 1| and since the shorting strip 10interconnects the straps 1|, 15 and 59, this end of the heater elementis placed in communication with the contact blades 11, 13 and 6|. Oneend of the heater unit B is connected to the terminal strap 83 and thusto the contact blade 66. The other ends of each of the heater units Aand B are joined together and are connected to the terminal strap 5|.Inasmuch as the terminal strap 5| is electrically connected to the strap4B by the shorting strip 56, the contact blades 49 and 54 areelectrically connected between the heater units A and B.

In connecting the heater system and switch to a power source, athree-line power supply is employed, designated by the lines L1, L2 andN. Customarily, the N line is a neutral, and the voltage across thelines L1 and Lz is of the order of 220 volts while that from either ofthe lines L1 or In to the line N is of the order of 110 volts. In thismanner various voltages may be impressed on certain of the heater unitsto attain a Widevariety of heating values from the heater system. Toconnect the switch to the power source the line L1 is connected to theterminal 21, the line L2 to the terminal 40 and the line N to theterminal 35.

The various positions of the switch and various heating values attainedfrom the heater system are shown diagrammatically by Fig. 9, althoughthe off position is shown diagrammatically by Fig. 7 as well as Fig. 9.When the switch is moved to the first or speed position, current flowsfrom the line L1 through the contact blade 49 to a point between the twoheater units A and B Where the current divides, one portion flowingthrough the heater unit B, contact blade 66 to the line L2, the otherportion owing through the heater unit A, movable contact 13 to the lineLe. In this manner, both the heater units A and B are subjected to thefull voltage across the lines L1 and L2 so that a maximum output fromthe heater system is attained. Various other positions oi the switch andthe heating values attained from the heater system will be manifest froman examination of Fig. 9. In the second or medium position the heaterunit B is placed across the lines L1 and L2. In the third or lowposition of the switch, both the heater units A and B are connected inseries across thepower lines L1 and Lz. In the fourth or cook positionof the switch, the heater unit B is connected across the lines L2 and N.In the fifth or warm position the heater units A and B are connected inseries across the power lines L2 and N.

While the invention has been shown and described as incorporated in aswitch having six positions for controlling a two-unit heater system, itshould be apparent that the switch may be adapted to controlr heatersystems having other arrangements of the heater units. For example, inFigs. 5, 8 and l0 a five-position switch is shown as controlling thecurrent to a plurality of heater units C, D and E.

The switch shown by Fig. 5 is in all respects similar to that shown byFigs. 1 to 4, inclusive, with the exception that the shorting strip 56is omitted and the shorting strip 'l0 interconnects the terminal straps59 and 15, only, and is hereinafter designated 10. One other change ismade in the fixed contact member 33 by omitting the contact arm 36 andthe contact button 38. In place of these elements a contact arm |06having a contact button 38 is secured to the cover 26 of the switch by ascrew |01, and this contact is electrically connected to the terminalmember 21 by a shorting strip |08 which lies against the inner face ofthe cover plate.

The operating cam disks for the movable contact blades are changed tothe forms shown by Fig 8 corresponding to the number of positions towhich the switch isI to be moved, in this case five, and are designatedby the numerals 9| to 96. inclusive. The four on positions of the switchare designated by the dotted lines I, 2, 3 and 4. The points at whichthe cam disks 9| to 96', inclusive, are formed with depressed portionsto permit closure of the movable contact blades will be apparent from anexamination of Fig. 8. Of course, the star wheel of the positioningmechanism is changed to provide five indexing depressions correspondingto the number of lpositions to which the switch may be turned.

The modified form of the switch has been shown in one use as controllingthe current to the oven heater units of an electric range, for example,the units C, D and E. The source of supply is a three-wire supply systemsimilar to that employed in the six-position switch previouslydescribed. The heater units C and D are customarily placed at the top ofthe oven, while the heater unit E is placed at the bottom of the oven.In connecting the heater units to the switch, one end of the unit C isconnected to the terminal strap 15 and by means of the shorting strip l0to the terminal member 59. In this manner the contacts 6l and 71 areelectrically connected to the said end of the heater unit C.

The other end of the heater unit C is connected to the terminal strap'll and thus to the movable contact 13. One end of the heater unit E isconnected to the terminal strap 46 and thus to the movable contact blade49. Similarly, one end of the heater unit D is connected to the terminalstrap 5l and thence to the movable contact blade 54. The other ends ofthe heater units D and E are electrically connected together and arelikewise connected to the terminal strap 63, and thus to the movablecontact blade 66. The threepower supply line is connected to the switchby connecting the neutral or N line to the terminal member 33, the lineL1 to the terminal member 2T and the line L2 to the terminal member 40.

I'he various positions of the movable Contact blades in the fivepositions of the switch are shown diagrammatically by Fig. l0 and theoii position of the switch is shown by Fig. 8 as well as by Fig. 10. Inthe first or Ipreheat position current flows from the line L1 throughthe contact blades 49 and 54 to one side of each of the heater units Dand E, and thence from the other side of these units to contact blade 66and line L2. In this manner the heater units D and E are placed inparallel across the 220 volt lines L1 and L2. In the second or cold ovenposition of the switch, the heater unit C is subjected to a potential ofvolts across the power lines L2 and N, while the heater unit E is placedacross the heater lines L1 and L2. In the third or hot oven position ofthe switch only the heater unit E is placed in the circuit across thelines L1 and Lz. In the fourth or broil position of the switch theheater units C and D are placed in parallel across the parallel lines L1and L2.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

1. In an electric switch, a housing having a recess therein, a pluralityof terminal members arranged around the periphery of said recess,stationary contact means secured to said terminal members, at least oneof said terminals having two integral arms extending in oppositedirection and each carrying one of said stationary contact means, aplurality of dexible spring contact blades co-operating with saidstationary contacts, and cam means for operating said spring contactsinto and out of engagement with said xed contacts.

2. In an electric switch, a housing having a recess therein, a.plurality of terminal members arranged around the periphery of saidrecess, stationary contact means secured to said terminal members, atleast two of said terminal members having two integrally formed arms,each arm carrying one of said stationary contacts, a plurality offlexible spring contact blades co-operating with said stationarycontacts, and cam means for operating said spring contacts forengagement with said fixed contacts.

3. In an electric switch, a housing having a recess therein, anoperating member having a plurality of cam surfaces disposed in saidrecess, a plurality of terminal members each having two stationarycontact arms, said terminal members being disposed symmetrically aroundsaid operating member with the contact arms of each terminal memberbeing arranged at two different levels and a plurality of ilexiblespring contact blades disposed symmetrically around said operatingmember and co-operating with said stationary contacts, said contactblades being arranged at two different levels for engagement with saidstationary contacts. 1

4. In an electric switch, a housing having a recess therein, anoperating member having a plurality of cam surfaces disposedsubstantially centrally of said recess, three terminal members eachhaving two integrally formed stationary contact arms, said terminalmembers being disposed symmetrically around said operating member withthe arms of each terminal member being arranged at two different levels,six flexible spring contact blades disposed symmetrically around saidoperating member and co-operating with said stationary contacts, saidcontact blades being arranged in groups of three at two different levelsfor engagement with said stationary contacts.

5. In an electric switch, a housing having a recess therein, anoperating member having a plurality of cam surfaces disposedsubstantially centrally of said recess, a plurality of terminal memberseach having two stationary contact arms, said terminal members beingdisposed symmetrically around said operating member with the arms ofeach terminal member arranged at two different levels, and a pluralityof U-shaped flexible spring contact blades disposed in pairssymmetrically around said operating member and co-operating therewith,said contact blades being arranged at two diierent levels with the bendsof the U of the contact blade of each pair extending in oppositedirection for co-operation with said stationary contacts,

6. In an electric switch, a housing having a recess therein, anoperating member having a plurality of cam surfaces disposed in saidrecess, three terminal members each having two integrally formedstationary contact arms, said terminal members being disposedsymmetrically around said operating member, with the arms of eachterminal member being arranged at two different levels, and six U-shapedflexible spring contact blades disposed in pairs symmetrically aroundsaid operating member, and co-operating therewith, said contact bladesbeing arranged in groups of three at two different levels with the bendsof the U of the contact blades of each pair extending in oppositedirections whereby said contact blades co-operate with said respectivestationary contacts.

7. In an electric switch, a housing having a recess therein, rst, secondand third terminal members each being disposed within said housing andeach having two contact arms forming stationary contacts, a. pair offlexible spring blades disposed between the rst and second of saidterminal members, the second and third of said terminal members and thethird and first of said terminal members, and rotatable cam means'insaid recess located centrally of said pairs `of contact means andco-operating therewith to 'move said contact blades into and out ofengagement with said stationary contacts, each blade of said pairsco-operating with a corresponding stationary contact.

8. In an electric switch, a housing having a substantially rectangularrecess therein, rst, second and third terminal members disposed withinsaid housing and each having two integral arms forming stationarycontacts, the first and sec- ,ond of said terminal members being locatedat opposite corners of said recess at one side thereof, and the thirdterminal member being located on the opposite side of said recessintermediate said first and second terminal members, a plurality ofpairs of exible spring contact blades in said recess, one pair beinglocated between said first and second terminal members, another pairbeing located between said second and third terminal members and stillanother pair being located between said third and first' terminalmember, each contact blade of each pair co-operating with acorresponding stationary contact, and rotatable cam means disposedsubstantially centrally of said contact blades and co-operatingtherewith to move them into and out of engagement with said stationarycontacts in a predetermined sequence.

9. In an electric switch, a housing having a recess therein, fii'st,second and third terminal members each being disposed within saidhousing and each having two integral arms forming stationary contacts, afirst contact blade located between said first and second terminal.members and co-operating with one of the contact arms of said firstterminal member, a second contact blade located between said first andsecond terminal members and co-operating with one of the contact arms ofsaid second terminal member, a third contact blade located between saidsecond and third terminal members and co-operating with the other of thefixed contacts on said second terminal member, a. fourth contact bladelocated between said second and third terminal members and co-operatingwith one of the fixed contacts on said third terminal member, a fifthcontact blade located between said third and first terminal members andco-operating with the other contact on said third terminal member and asixth contact blade located between said third and first terminalmembers and co-operating with the other xed contact on said firstterminal member, and rotatable cam means located substantially centrallyof said contact blades and co-operating therewith to force them into andout of engagement with said stationary contacts in a predeterminedsequence.

10. In an electric switch, a housing having a recess therein, first,second and third terminal members each being disposed within saidhousing and each having two integral arms forming stationary contacts, afirst contact blade located between said rst and second terminal membersand co-operating with one of the contact arms v of said first terminalmember, a second contact blade located between said first and secondterminal members and co-operating with one of the contact arms of saidsecond terminal member, a third contact blade located between saidsecond and third terminal members and co-operating with the other of thefixed contacts 0n said second terminal member, a fourth contact bladelocated between said second and third terminal members and co-operatingwith one of the fixed contacts on said third terminal member, afifthicontact blade located between said third and nrst terminal membersand co-operating with the other contact on said third terminal memberand a sixth contact blade located between said third and first terminalmembers and co-operating with the other fixed contact on said firstterminal member, rotatable cam means located substantially centrally ofsaid contact blades andA co-operating therewith to force them into andout of engagement with said stationary contacts in a predeterminedsequence, and a shorting member interconnecting said first and secondcontact blades and another shorting member interconnecting said third,fifth and sixth contact blades.

11. In an electric switch, a, housing having a recess therein, first,second and third terminal members disposed within said recess and eachhaving two arms forming stationary contacts, a plurality of pairs ofcontact blades in said recess, each contact blade being a U-shapedflexible springr strip and the blades of each pair being reverselyarranged relative to one another, a pair of said contact blades beingarranged between said rst and second terminal members, another pair ofsaid blades being located between said second and third terminalmembers, and still another pair of said blades being located betweensaid third and rst terminal members whereby a contact blade co-operateswith each of said respective fixed contacts, and rotatable cam meanslocated substantially centrally of said contact blades and co-operatingtherewith to move them into and out of engagement with said fixedcontacts in a predetermined sequence.

12. In an electric switch, a housing having a recess therein, first,second and third terminal members disposed within said recess and eachhaving two arms forming stationary contacts, a plurality of pairs ofcontact blades in said recess, each contact blade being a U-shapediiexible spring strip and the blades of each pair being reverselyarranged relative to one another, a pair of said contact blades beingarranged between said first and second terminal members, another pairor" said blades being located between sai-d second and third terminalmembers, and still another pair of said blades being located betweensaid third and first terminal members whereby a contact bladecoFoperates with each of said respective fixed contacts, rotatable cammeans disposed substantially centrally of said contact blades and aslider element mounted on each of said contact blades and co-operatingwith said cam means whereby said contact blades are moved into and outof engagement with said xed contacts in a predetermined sequence.

13. In an electric switch, a housing having a recess therein, first,second and third terminal members disposed within said recess and eachhaving two arms forming stationary contacts, a plurality of pairs ofcontact blades in said recess, each contact blade being a U-shapedflexible spring strip and the blades of each pair being reverselyarranged relative to one another, a pair of said contact blades beingarranged between said nrst and second terminal members, another pair ofsaid blades being located between said second and third terminalmembers, and still another pair of said blades being located betweensaid third and first terminal members whereby a contact bladeco-operates with each of said respective iixed contacts, a rotatableoperating element located substantially centrally of said contactblades, said element comprising a plurality of cam disks separated byplates of insulating material, each of said contact blades beingprovided with a slider element co-operating with a respective cam disk,the plates separating said disks guiding said slider elements intoengagement with said cam disks.

DONALD G. KIMBAIL,

